1. Field of the Invention
The present invention relates to a curved-surface processing or machining method for fabricating a smooth curved surface on a positive photo-resist layer which is formed on a surface of a workpiece, and an apparatus for the same.
2. Description of the Related Art
In recent years, micromachining technologies based on LSI manufacturing technology have been employed to attempt the processing of curved surfaces for ultra-compact optical lenses, acoustic lenses, and the like. These curved-surface machining technologies utilize laser beams, ion beams, and electron beams to fabricate a curved surface of the specified configuration by emitting and scanning of these beams on the surface of the workpiece.
However, as is shown in FIG. 9, with the method whereby the surface of a workpiece 32 is machined by scanning of a beam 31, the intensity profile of the beam 31 is a parabolic distribution which is strong at the center and becomes weaker on the periphery, and so traces of the beam scanning (minute striations extending along the direction of scanning) remain on the workpiece, and the machined surface becomes rough, making this unsuitable for the delicate machining demanded for the precision smooth curved surfaces of lenses and the like. Moreover, because beam scanning must be repeated many times to obtain the specified machining configuration, this has the drawbacks of long overall machining times and poor machining efficiency.
This invention has taken these circumstances into account, and an object is to provide a method for processing or machining curved surfaces capable of delicate machining of precision smooth curved surfaces on a workpiece with good efficiency, and an apparatus for the same.